This invention relates to paper feed mechanisms for printers or the like and, more particularly, to an improved pin feed roller assembly for accommodating a plurality of widths of paper having sprocket feed holes.
Computer printers or the like are known where the paper, or other print record medium, is incrementally stepped along a paper path. In such a printer, one requirement is that the stepping be precisely controlled to maintain proper registration of the lines of print on the paper. One way of accomplishing this result is to provide the paper with a series of equally spaced perforations along the edges thereof and to provide the printer with a roller having sprocket wheels or pin wheels, or rings, with circumferentially spaced pins on the periphery thereof. These pin rings, hereinafter referred to as sprocket wheels, engage the perforations of the paper to feed the paper while maintaining the required registration. An illustrative paper feed mechanism utilizing such an arrangement is disclosed in U.S. Patent Application Ser. No. 040,911 entitled: PAPER FEED MECHANISM FOR PRINTERS AND THE LIKE, filed May 21, 1979 by David M. Wolfe, and assigned to the assignee of the present invention. In the reference application, a pair of sprocket wheels are fixedly mounted near the opposite ends of a paper feed roller. Thus, only one width of perforated edge paper may be accommodated by such assembly. Different countries for example, have different standards regarding the hole to hole dimensions, vis-a-vis the width of the paper, for paper having sprocket feed holes. One way of providing for the acceptance of different width paper in a single printer would be to provide a plurality of roller assemblies, one for each of the different hole to hole dimensions measured across the width of the paper. It would be desirable, however, to provide a more economical and practical arrangement for accommodating these different width papers.
It is, therefore, a primary object of this invention to provide a pin feed roller assembly that can accommodate a plurality of widths of perforated edge paper.
In the prior art, there have been a number of attempts to provide a "universal" pin feed roller assembly. Some of these attempts involve adjusting the length of the roller by providing, for example, variable length threaded sections. Other attempts involve moving the relative position of the sprocket wheels which are secured to the roller by set screws or the like. However, all of these attempts involve the use of special tools and require making very precise adjustments. Accordingly, these adjustments require a skilled technician in order to be made accurately. It would thus be desirable to have an arrangement whereby even a relatively unskilled operator may simply and yet precisely adjust the pin feed roller assembly to accommodate a plurality of widths of paper having sprocket feed holes.
It is, therefore, another object of this invention to provide a pin feed roller assembly which may accommodate a plurality of widths of paper having sprocket feedholes and which may be precisely and yet readily and easily adjusted by an operator without requiring the use of special tools or training.